1. Field of the Invention
The invention relates to a fan hydraulic coupling for a water cooled motor with a temperature-dependent flow regulator, a driving shaft and a driven part coaxial thereto and carrying a fan wheel, the motor having a cooling circuit for a cooling fluid or coolant to cool the fan hydraulic coupling. The invention also relates to a hollow drive shaft for a coolant pump in the cooling circuit of the motor. The hollow drive shaft is connected at a first end to a cooling liquid circuit of the motor and at a second end to the hydraulic coupling for cooling the hydraulic coupling. The hydraulic coupling being connected to the hollow drive shaft through radial hollow shaft openings for exchanging cooling liquid.
2. Description of the Related Art
It is known to regulate or control the temperature of internal combustion engines and electric motors with the aid of a cooling fluid or coolant. In the case of water-cooled internal combustion engines a cooling circuit is provided, in which the coolant is constantly pumped. Cooling air is sucked from the outside by means of a fan and passed over the surfaces to be cooled.
In the case of internal combustion engines the fan wheel and pump impeller of the coolant pump are frequently driven by means of a common shaft. For regulating the speed of the fan wheel it is known to provide a temperature-dependent fluid coupling. Control takes place as a function of the external temperature or the sucked in cooling air. As the regulating process is based on a motor or engine-independent controlled variable, it is not unrestrictedly possible to adapt the cooling to the particular operating conditions and to the motor temperature to the desired and necessary extent.
A conventional hydraulic coupling is described in DE-3140195. The coupling is controlled as a function of the temperature of the cooling water, which is directed on a thermoelement close to the coupling by a fan gear shaft designed as a hollow shaft. For cooling, in the working chamber of the coupling there is a cooling coil which is supplied with cooling water by radial bores in a hollow shaft. Subject to design, this hydraulic coupling is relatively large and further requires a large amount of working fluid. There is a relatively small cooling surface in comparison with the relatively large amount of working fluid. Since an additional cooling element is provided in the working chamber, the field of application is limited for reasons of space. Moreover, as required by the system, a relatively large assembly, maintenance and material expenditure is necessary,.
Another temperature-controlled hydraulic coupling for a fan of an internal combustion engine is described in DE-420277. The control takes place with a bimetal element, which is exposed to the air given off by the fan. In this case, it is put outside on the coupling housing.